As far as astronomers can tell, there is very little antimatter in the observable universe (If there was more, we'd see it anihilating with matter more).

If we're not sure both sides of the conversation are made of the same particles, the situation is hopeless.

Aren't matter and antimatter a matter of perspective? If so haven't we just reintroduced the left/right problem.

Precisely.

They didn't explode when we shook hands (/tentacles/general-graspy-bits)